The present invention relates generally to the insertion of prewound coils in magnetic cores and more especially to the insertion of such prewound coils in dynamoelectric machine stator cores. More particularly, the present invention relates to a method and apparatus for the insertion of such prewound coils which is readily adapted to varying magnetic core dimensions.
A number of machines have been devised for inserting prewound coils, as well as, optionally, insulating wedges into stator cores. One such coil placing machine is illustrated in the Hill U.S. Pat. No. 3,324,536. In the Hill device, as in the present invention, preformed coils, for example formed on winding machines of a known type, are placed over appropriate tooling blades or fingers of the placer for subsequent insertion into a stator. The coils for all of the poles of the machine to be produced may be placed on the tooling blades and if desired auxiliary or start windings, as well as main windings, may be placed on the blades and inserted into the stator core by but a single axial pass of a stripper along the blades to engage and urge those windings into and partially through the stator core. Various insulating wedges may be inserted into the stator core slots, either to separate windings or to isolate the windings from the stator bore, and such insertion processes may be effected in a single stage operation or in several stages as desired.
The above-mentioned Hill coil placing machine provides for rather rudimentary modifications to accommodate stators of different stack height. To maintain the end turns of the coils at a reasonable minimum when they are positioned in a stator, and of course to accommodate a given coil within the stator for which it is designed, the finger elements or blades should extend about to or just beyond the stator end face and similarly the maximum extension or travel of the stripper through the stator bore should be at most only slightly beyond that necessary to place the windings into the stator. To obviate these potential problems when changing from one stack height to another, the Hill machine provides for the insertion of tubular spacers of a preselected length in conjunction with a certain amount of lost motion in the connection between a stripper actuating ram and the stripper so that the length of the stroke taken by the stripper is appropriate to the particular axial length of the stator being then provided with windings. Similarly, the Hill device provides for adjustment movement of the finger elements or blades and also of so-called wedge guide members by loosening a plurality of screws which hold those fingers and wedge guides in place and this type operation amounts to the individual repositioning or removal of the pertaining blades and guides. While effective, this blade and wedge guide adjustment process was sufficiently time consuming and difficult that an arrangement for simultaneously gripping and moving the blades when the screws were loosened was devised and is disclosed in the Walker et al U.S. Pat. No. 3,402,462.
There have been further attempts to simplify the process of accommodating such a coil placing machine to operate on stators of varying stack height. For example, adjustment of the blades or finger elements by using a centrally tapped blade holder and a threaded tooling shaft, rotatable by a wrench, have been used in several versions with U.S. Pat. No. 3,698,063 being exemplary of such approaches. Typically, the stripper must be removed to allow access by the wrench to make the adjustment.
Also, special machines, for example as illustrated in U.S. Pat. No. 3,829,953, have been designated to achieve multiple adjustments simultaneously. The exemplary patented device employs a chain driven set of variable height control surfaces and an axial stripper drive shaft including a slip clutch connection. This exemplary device varies the height of the stator clamping arms, wedge length, the stroke of the stripper, and the tooling blade axial extent. The approach of this last-mentioned exemplary patented device is not easily adaptable to the vast number of machines already in the field and is rather costly in its implementation.